Slackless type drawbar assemblies have been well known in the railroad industry for several years as a means to connect together the adjacently disposed ends of a pair of railway freight cars in a substantially semi-permanent fashion, prior to the development of the present invention.
In other words, these railway freight cars do not require frequent separation during service. Normally they will only be separated during a required repair and/or routine maintenance being performed on one or more of them.
These particular railway cars are normally of the type used in what is most commonly referred to, in the railroad industry, as dedicated service. Railway freight cars of such dedicated service type will at least include: those cars which are normally utilized to haul coal, coke, and/or various other types of raw minerals; automotive type transport carriers; cars which are utilized in the transporting of various types of building materials and tank cars which are used to transport various types of liquid products.
Examples of some other raw minerals transported in these dedicated service railway freight cars include: various ores, cement and stone. The various types of liquids transported by such dedicated service railway tank cars will at least include a number of different chemicals. Building materials transported in this manner include: lumber, dry wall, plywood, paneling, etc.
A typical slackless type drawbar assembly using a ball and race connection assembly comprises the following elements: a car connection member engageable with a railway vehicle, a spherical member securable with the car connection member, a male connection member having a curved butt end and an aperture which is disposed around the spherical member secured with the car connection member, a race assembly secured within the aperture of the male connection member and disposed between the spherical member and such aperture, and a drawbar connected to such male connection member.
The outer surface of the spherical shaped member, or ball member, has a sufficiently smooth surface. Currently used ball member surfaces can be electroless nickel plated, chrome plated, or the like to improve the corrosion resistance of the ball member. The race assembly of such currently used slackless type drawbar assemblies, comprises a metal member having a machined surface. This race assembly is secured within the aperture of the male connection member and surrounds a portion of the ball member so that the ball can rotate within the race assembly and aperture and the adjacently disposed freight cars can obtain the requisite amount of angling movements and readily maneuver with respect to each other during their operation on a track structure.
In order to ensure unrestricted movement of the ball member within the race member, care must be taken to ensure that the contacting surfaces are machined to a requisite smoothness. Additionally, adequate lubrication must be provided between the ball member surface and the inner surface of the race member. Any well known techniques of applying lubricating materials between rotating surfaces may be used. One known technique for obtaining this lubrication is to provide a substantially solid type lubricating liner member, such as manufactured by Kahr Bearing Co. and marketed by them under the trade name “KARLON”, disposed between the outer surface of the spherical shaped member, or ball member, and the inner surface of the race assembly.
Although many lubricating techniques are well known in the art, it is still difficult to maintain a reduced amount of friction between rotating metal to metal surfaces. Additionally, machining of both the ball member and the race member to sufficient smoothness and continuously providing adequate lubrication between the ball and race surfaces can be costly and time consuming.
The railway industry is continuously seeking ways to cut costs whether these cuts be in the cost of materials, labor manufacturing costs, and/or in maintenance costs. Another way to cut costs is to reduce the weight of the freight cars and the components for connecting the cars together. This reduction in weight allows for a reduction in the amount of energy or fuel used to pull the train which ultimately results in higher payloads. Although higher payloads are the ultimate goal of manufacturers, a high level of safety must be maintained.
One way to measure the safety of the railway vehicle is through what is known as an L/V ratio which is the lateral force over the vertical force of the vehicle. An acceptable L/V ratio limit as set by the Mechanical Committee of the Standard Coupler Manufacturers (MCSCM) is 0.82 and the recommended L/V ratio limit is less than or equal to 0.74. As manufacturers reduce the weight of the cars and/or the loads carried by these cars, care must be taken to ensure that the L/V ratio is not exceeded. If the L/V ratio exceeds the acceptable limit, the lateral force on the car(s) during turning can exceed the vertical force of the car's weight on the wheels thus causing the wheels of the car(s) to lift off of the track and the train to derail.
One of the ways in which an L/V ratio can be reduced is by reducing the amount of friction in the joint between the male and female connection members of the drawbar assemblies.